They use zone ratings, meaning balls hit into a certain zone that should be fielded by the average player at that position. I can't say that I can recall bunts and dribblers that he should've fielded but didn't, but I assume that's what cost him. He only has 3 errors and 6 passed balls in 85 games. Who knows.

I had a theory that Molina's strong arm caused less SB attempts, thus limiting the number of runs he prevents in the system.

However, it appears that not only is Molina throwing out runners at a great percentage (44), but runners are actually attempting SBs on him more than the average catcher!

In the entire AL, there have been 17,405 IP this season, and 1575 SB attempts. That equates to one SB attempt every .09049 IP.

Molina has caught 659 innings this season, with 68 stolen base attempts him, or one attempt every .1031866 IP.

Given Molina's innings caught and the AL average, he should have 60 SB attempts against him. So, AL baserunners have attempted 13% more SBs against Molina than against the average catcher, despite the fact that Molina is great at throwing out attempted base-stealers!

The AL average for throwing out runners is 27%. Given Molina's 68 attempts against, an average catcher would have thrown out 18 base-stealers. Molina has thrown out 30.

I can't imagine he's been THAT bad on plays in the field that it nagates everything he's done to neutralize opposing running games